marktc

Dynojets use a correction factor that can easily be manipulated by the operator. They consistently read higher because of the correction factor. Most Dynojets use a 1.15 correction factor in order to determine crank hp. I could go into great detail as to why the correction factor is silly and how they came up with it. That being said, any dyno can have numbers manipulated. However, if you ask around, Dynojets usually read 5-15% higher than a mustang, dynapac or any other eddy-current type dyno. The basic idea as to why it is assumed that Dynojets read more accurately is because they measure hp by determining the increase in rotational speed per rpm given a defined mass (the mass of the drum that the wheel is spinning.) so.. In theory, the dynojet should be the most accurate.. But, due to the simplicity of adjusting the correction factor and the constant need for shops to say that they have created the most powerful car.. It gets abused. The only way to be certain is to do a before and after on the same dyno. At least that way, you can see what kind of increase you have. (Yes.. There are humidity changes, barometric pressure changes, temperature changes etc.. To contend with)

You would be surprised how many people don't know that.

^Bang on.. for those who don't know --- HP = Torque/5252*RPM

I agree.. I apologize.

Gallardo Twin Turbo.

I know it is.. That's why I cautioned about the rumor etc.. Its not a statement.. and perhaps I should simply edit it out. The fact does remain that the car went through three engines. And.. Heffner, to my knowledge, no longer uses piggy back's on their top end kits anyway. So.. the point is only about piggy backs.. nothing to do with Heffner.

Yes. I'm saying they went through 3 engines. I do not know the extent of the build of the engine in each case. However, I know the individual and money was not an issue, so, I doubt he spared any expense. Now, on the other hand, I do understand how Piggy-Backs work and it's not surprising to me that the engines blew up. The rumor that was spreading had to do with the knock sensor inputs not being properly interrupted and the factory engine ECU was significantly retarding ignition timing causing a serious increase in EGT and cylinder combustion temps which resulted in significant internal engine damage. Now, please understand the last statement is ONLY A RUMOR. Also, I cannot say that the individual didn't do any additional tweaking on their own. So, it is entirely possible that person used the race fuel tune with premium gas, or cranked the boost up to see what could be achieved on the dyno. But, again, this is truly symantics. Piggy-Back systems are limited at best. When I was shopping for a standalone for my Esprit, I talked with manufacturers about the idea of piggy back systems to keep the budget down. Each of them advised me against it. The additional cost of running a proper standalone is insignificant when compared to the cost of a new engine.

Thanks Limey. I am always here to help if anybody asks. I am currently only working on my own vehicles at the moment. I will post my build on my diablo soon though.

sorry.. double posted

Just an added note to the standalone vs piggy-back. There is a local guy who is on his 3rd engine from the Heffner kit. I could go into great detail, but I will try and keep it simple. The piggy back ecu's try to trick the factory ecu's into thinking one thing is happening in order to make the factory ECU add more fuel, pull timing etc.. Well, VAG systems are highly intelligent and figure out that something is wrong when the knock count starts to get out of range or the cam phase sensor isn't matching the crank phase sensor or the Intake air temp is outside of parameter when compared to the outside air temperature sensor for the Body Control Module.. etc.. etc.. etc.. With a high quality stand alone, you can send the necessary can-bus information to the BCM to make the car think it still has factory ECU's. And, with the Diablo, the GFA is actually the source of a lot of the problems with the factory ECU's.. The GFA monitors EGT and Misfire sensors that the factory ECU does not. So, it sends a write command to the factory ECU (just like a piggy back). Now, this causes additional problems. If you have mild mis-fires, it sends signals to change fueling. This means that the computers ability to monitor itself in closed loop with O2 sensors is all but completely eliminated. So, what happens next? Bank 1 or bank 2 too rich/lean code. Now, if you have misfires, you will clog up a catalytic.. VERY FAST. This will result in a cat that will cause massive back pressure.. resulting in more misfires and more fuel. The loop continues until the CAT explodes.. Now.. guess what happens next.. the EGT sensor detects that the cat isn't getting hot (because there isn't one anymore) and the GFA tells the ECU to add EVEN MORE FUEL. So.. Diablo owners are actually quite familiar with what a Piggy Back system can do..

AWESOME!!!!!

AWESOME!!!! Will you be making the wastegates open-dump on a seperate set of pipes?

(second post due to user error)

That's actually an Esprit interrior.. I might have to do that conversion to my Esprit and replace the horrendous pontiac firebird steering wheel that it came with from factory